Distribution amplifier connected to HD projector and SD projector

[colejer]

Hi guys,

Will a distribution amplifier that is connected to both an HD projector and an SD projector push the HD projector to the lower resolution of the SD projector?

Have not bought the DA yet, it will be from extron or gefen.

Thanks

[petereit]

All depends on what signal you send to your DA. If you send it an SD signal, your HD projector should scale it up, but it will not be HD. If you send an HD signal, your SD projector more than likely won't know what to do with it and either display garbage or nothing at all.

[colejer]

We want to send an HD background through Propresenter running on a mac. Someone told me there might be a DA that has a downscaler from Matrox where we could run one in HD and the other in SD until we have enough to buy both HD projectors.

[sempei13]

I really think it's more likely that you'll get bad results in SD. Probably you best option is source>DA>HD projector and Scan converter>SD Projector.

If the DA has the ability down scale, be careful that it doesn't down-scale everything. The HD projector might scale up an SD signal, but its always worse to go up and down and up, etc than stay up or go from up to down.

Paul

[petereit]

Just for what it's worth -- you can't tell the difference between a true HD projector and a MUCH cheaper WXGA projector from 20 feet. Might save you a bundle upgrading your SD projector to WXGA.

[Brad Weber]

Originally Posted by petereit

Just for what it's worth -- you can't tell the difference between a true HD projector and a MUCH cheaper WXGA projector from 20 feet. Might save you a bundle upgrading your SD projector to WXGA.

For one thing, I believe that "WXGA" defines 1280x768, but for projectors commonly is used to describe 1280 to 1366 horizontal and 720 to 800 vertical native resolution projectors. 720p HD is 1280x720 resolution so a "WXGA" projector is a true HD projector.

Also consider that the effect of resolution is going to be a factor of both the viewing distance and the image size, the two are interrelated and both should be considered. This was a very common issue when we had lower resolution projectors as people would often a large format projected image from a foot or two away and expect it to look like their 17" monitor viewed from the same distance, not thinking that everything was magnified by some factor so that the image could serve a correspondingly larger viewing distance.


To expound on Paul's point, unless the projector supports, and you select, direct pixel mapping then any projector is going to internally 'scale' the incoming incoming signal to its native resolution. A 1024x768 projector may accept a wide range of input signal resolutions but it will usually internally 'map' or process any incoming resolution to its own 1024x768 native resolution. So, if you send 1920x1080 (1080p HD) to a 1024x768 projector it may accept that HD signal, but will display it as a letterboxed 1024x576 resolution image, using processing to reduce the resolution of the image to match the display, in effect using image processing to determine what pixels to average, throw out, ignore, etc. Conversely, a 1920x1080 native projector sent a 1024x768 signal will internally process that 1024x768 resolution image via interpolation and other image processing to add the pixels necessary to create a pillarboxed 1440x1080 image to match the projector's native resolution.

So as long as both projectors will accept the signal resolution being sent to them, the HD>SD and/or SD>HD conversion is going to happen in the projectors, the question is really whether it might be better handled by a dedicated device.

[petereit]

Originally Posted by Brad Weber

For one thing, I believe that "WXGA" defines 1280x768, but for projectors commonly is used to describe 1280 to 1366 horizontal and 720 to 800 vertical native resolution projectors. 720p HD is 1280x720 resolution so a "WXGA" projector is a true HD projector.

Yes, but I have found that slapping the industry-approved "HD" label can sometimes add $1,000 or more to the price tag. And going full 1080p is simply not necessary for 99% of church projection needs since that additional resolution cannot be perceived beyond 20 feet.

[Brad Weber]

Originally Posted by petereit

Yes, but I have found that slapping the industry-approved "HD" label can sometimes add $1,000 or more to the price tag. And going full 1080p is simply not necessary for 99% of church projection needs since that additional resolution cannot be perceived beyond 20 feet.

I agree that full 1080p is rarely necessary or even that beneficial in many applications, but every resource I have seen relating the perception of different resolutions to viewing distances also involves the image size. For example, this chart (http://s3.carltonbale.com/resolution_chart.html) suggests that the benefits of 1080p over 720p may not be perceived at a 20' viewing distance with up to a 100" diagonal (a nominal 49" high by 87" wide, 16:9 image) but may be discernible at that same 20' viewing distance for an image larger than 100" diagonal.

The reality is that many display systems properly designed to handle computer graphics are also often capable of handling HD video. I recall one project where the video production person refused to believe that the 1280x720@60Hz, 720p signals their "HD" SDI video production system would provide would not be a controlling factor for the video display and projection systems and would not require upgrading those systems. The reality was the inverse, the computer graphics resolutions they wanted the display systems to support would allow upgrades to the video systems.

[colejer]

Thanks for all the good comments.

I should be a little more specific as I am concerned about a digital and analog signals. Here is our planned signal flow. We have two computers connected HDMI to our switcher Sony MCS-8M going out through the DVI-D aux to our Extron DVI Distribution Amplifier. From there we want it to go DVI to 3 TV's and our two projectors. Our new projector is a Sony VPLFH500L which has a DVI input (no HD-SDI input) and we have an older VGA short throw projector that has only analog inputs (no HDMI or DVI, we currently use VGA). Since we are sending a digital signals from the Switcher through the DA to the projectors I don't think the analog projector is going to work and we would have to buy a DVI digital convertor to VGA analog signal or we could buy a new projector that has a digital input like HDMI or DVI. Is that correct?

All the equipment is not bought yet so we can accept recomendations on how to make it better but realize that our church is in Dubai and we don't have access to a lot of equipment and servicing that you have in the USA. I originally suggested a 720p projector from Digital Projection based only on specs and price but due to purchasing locally and servicing if it breaks we decided to go with Sony as they have their servicing for the middle east in Dubai and we could buy everything locally so if it breaks we have someone to take care of us. Basically the ability to buy and get it serviced locally won out over price and specs.

I was trying to find a way to connect everything HD-SDI but none of our projectors or TV's have that input. Is HD-SDI better and if so does anyone know of a workaround to make it happen? Is it worth it?

Thanks
Jeremy

[Brad Weber]

Jeremy, you are correct that other than the one composite video the video outputs of your switcher are apparently digital, either SDI or DVI-D, therefore your projectors and 'TVs' would need to accept one of those signals or some intermediate conversion would be required. There are some devices available such as the HDFury products and the Altinex VP500-100 intended to be connected to directly to VGA/RGBHV inputs and 'convert' them to HDMI inputs.

In addition, the switcher is also fairly limited in the output formats it supports with only 480i/59.94 and 576i/50 SD and 720p/50, 720p/59.94, 1080i/50 or 1080i/59.94 HD signals available. The switcher's inputs are similarly limited to being compatible with 720p/50, 720p/59.94, 1080i/50 and 1080i/59.94 signals for the HDMI inputs and to 1080p/50, 1080p/60, 1024x768/60, 1280x768/60 and 1280x1024/60 signals for the DVI-I inputs. This is fairly common and while most projectors, monitors and flat panels accept and display a wide range of signals, production style 'multiformat' switchers tend to be much more limited in their compatible signals especially in regards to computer sources and outputs, the latter of which tend to be standard 'video' rather than computer formats.

As a result, you are going to have to consider not just the compatibility of VGA/DVI/HDMI/etc. but also the compatibility of the resolutions and refresh rates. For example, all of your display devices would need to be compatible with whatever single switcher output format is selected from among the two SD and four HD formats available. This is also where you may likely have to rely on the scaling in at least some of the display devices as it is generally not be possible to select a resolution out of the switcher that would match the native resolution of all the attached destination devices. That seems to be applicable to your situation as none of the output formats supported by the Sony MCS-8M switcher match the native resolution or format of your 1920x1200 resolution, 16:10 format VPL-FH500L projector, although one of the 1080i output options would match the projector's native horizontal resolution.

Another potential consideration is that HDCP is not supported by the switcher's DVI or HDMI inputs. In many applications this may not be a factor but it can be an issue for some computers, Blu-Ray players, satellite and cable TV receivers, etc. sources that may not output HD signals on their HDMI or DVI outputs if they are not connected to a HDCP compatible input.

This is not intended to make it sound overly challenging, rather to address that systems like those apparently planned have to consider more than just what type of connectors are involved and it really does make sense to plan carefully. It is not at all unusual for me to end up assessing multiple possible solutions for such systems in order to determine which one may be the most appropriate and cost effective.